[Photo provided to China Daily]

Jiang Qitao, the scriptwriter, spent a year looking through files and flew to Taiwan to meet people who knew about Zhang's later years.

"Zhang's life is pretty colorful. Even 100 episodes cannot cover all the tales and anecdotes," says Jiang.

Zhang Li, the director, says the crew finally decided to follow a storyline that "revolves on a young man's unlikely formative years".

The director is known for such historical dramas as Ming Dynasty in 1566 and For the Sake of The Republic of China. He believes the key to success in historical dramas lies in being faithful to the spirit of the story, not just recreating the facts.

"Zhang was betrayed by his best friend and forced to marry a woman he'd never known. While most young men of his age lived carefree lives then, he has to shoulder the responsibility to lead Northeast China," the director says.

"He was the kind of guy who lived amid struggles and suffered."

While Zhang Xueliang remains a controversial subject with historians, another kind of controversy haunted the man who was to play him - Wen Zhang.

When Wen took the job in 2014, he was caught up in a scandal of cheating on his pregnant wife with another actress.

Also, very few in the industry believed then that Wen would be a good choice to play a powerful marshal.

But Wen, 32, worked hard to prove himself.

Despite being born in Northwest China's Shaanxi province, he learned the northeastern dialect and spent time in the US researching Zhang's last years.

In the scenes featuring Zhang's drug addition, Wen ate and slept very little for two weeks to portray his character's exhaustion.

The cast also features award-winning actor Li Xuejian (Zhang Zuolin) and veteran actress Song Jia (Yu).

The latest statistics show the series at second spot on the nationwide ratings of the TV dramas.